Introduction
The test battery for (C)APD is categorized into five categories namely dichotic tests, auditory temporal processing and patterning tests, binaural interaction tests, monaural low-redundancy tests, and electrophysiologic tests (Baran, 2007). Dichotic tests such as Dichotic CV, Dichotic digits, Dichotic rhyme, Dichotic word and Dichotic sentences are usually used to assess binaural integration (Bellis, 2003). Dichotic CV is language independent and a standardized test which is commonly used to assess binaural integration abilities (Yathiraj, 1999). The binaural integration abilities could be different in musicians and non-musicians.
Need for the study
Musicians are a group of individuals who are trained to perceive fine structural variation in the acoustic stimuli. It is well reported in the literature that musical training enhances the ability of coding fast varying auditory signal (Strait, O’connell, Parbery-Clark, & Kraus, 2013). The role of musical training has also been studied extensively in the context of auditory skills, including auditory streaming (Zendel & Alain, 2009).
However, there are no studies reported in the literature which have attempted to understand binaural integration abilities in musicians. Thus, the aim of the present study was to analyze the differences in binaural integration abilities using Dichotic CV test in individuals with and without musical training. The study also attempted to determine if there are any correlations between number of years of musical training and Dichotic CV scores.
Method
A standard group comparison was adapted by considering 60 individuals with normal hearing within the age range of 15-30 yrs. The participants were divided into 2 groups: Group 1 consisted of 30 musicians and group 2 consisted of 30 non-musicians. Binaural integration abilities were tested using Dichotic CV test developed by Yathiraj (1999). Pair of monosyllables was presented dichotically and the participants were asked to identify both the monosyllables. Based on their response, single correct scores for right and left ear and double correct scores were determined. The obtained scores were compared between both the groups. The testing was carried out at 60 dB HL in a sound treated room. Informed consent was taken from all the participants of the study.
Results and Discussion
Shapiro Wilk test of normality suggested that the data was normally distributed (p>0.05). Independent t-test was carried out to compare the scores of Dichotic CV test between the two groups. The results of the study showed that the scores were significantly better (p<0.05) in musicians compared to non-musicians. The effect size was calculated using the formula r=Z/√N. The effect size was found to be 0.81 which shows that the significance is strong. In addition, Pearson’s product moment correlation was done to determine if there is any correlation between the scores and the number of years of music training. The result of the correlation analysis shows that the scores were better with increase in duration of music training.
Studies have also shown that musicians have enhanced temporal perception (Rammsayer & Altenmüller, 2006), speech perception in noise (Jain, Mohamed, & Kumar, 2015) and better fine structure abilities (Mishra, Panda, & Raj, 2015). It is reported that training can induce neuro-plastic changes in the cortical processing (Cheng et al. 2017). Binaural integration process happens at the level of auditory cortex. Thus, the improved binaural integration in musicians could be because of structural and functional superiority in musicians because of neuro-biological changes in the central auditory nervous system.
Conclusions
The present study attempted to determine if there are any differences in binaural integration abilities between musicians and non-musicians. The results of the study showed that binaural integration was better in musicians compared to non-musicians. In addition, it was also found that the number of years of music training correlated with the scores on Dichotic CV test. Thus, binaural integration was found to be better in musicians compared to non-musicians and scores improved with increase in number of years of training. However, further studies are essential on a larger group with more variables for validation of the results.